In this paper we present an assistive system designed for supporting young children affected by autism in their process of learning pronunciation and meaning of new words. The system is built-up of a mobile application and objects identifiers which in our case were Estimote Beacon sensors. The system requires active participation of a parent who selects words to learn, records pronunciation of object names, selects illustrations, and activates and turns off the application. The entire process is designed to extend parents’ care and to support autistic children with an instant repetition of pronounced object’s names when those items are met during playing or moving around the house. An experimental part of our project consists of a report where we compare collected results of two autistic children using our application installed on a smart watch and on a smart phone. In both reported cases autistic children made a visible progress in speed of learning new words when compared to an equivalent period of time without assistive application support.
Peer-to-Peer (P2P) networks face the challenge of frequent pollution attacks. In such attacks, malicious peers pollute the network by sharing mislabeled, corrupt or infected content in an attempt to disrupt the system and waste network resources. When faced by such phenomenon, regular peers get discouraged from participating in the P2P network as they find less value in the system. In this work, we investigate the amount of resources required to restrain pollution attacks by means of content validation. We introduce multiple adaptive techniques that can minimize the spread of polluted content, while at the same time reduce the cost of content validation for peers participating in the network. Furthermore, the proposed pollution-restraint techniques are resistant to collusion from malicious peers, and they do not contribute to excessive communication overhead in the P2P network. 相似文献
Advances introduced to electronics and electromagnetics leverage the production of low-cost and small wireless sensors. Wireless sensor networks (WSNs) consist of large amount of sensors equipped with radio frequency capabilities. In WSNs, data routing algorithms can be classified based on the network architecture into flat, direct, and hierarchal algorithms. In hierarchal (clustering) protocols, network is divided into sub-networks in which a node acts as a cluster head, while the rest behave as member nodes. It is worth mentioning that the sensor nodes have limited processing, storage, bandwidth, and energy capabilities. Hence, providing energy-efficient clustering protocol is a substantial research subject for many researchers. Among proposed cluster-based protocols, low-energy adaptive clustering hierarchy (LEACH) and threshold LEACH (T-LEACH), as well as modified threshold-based cluster head replacement (MT-CHR) protocols are of a great interest as of being energy optimized. In this article, we propose two protocols to cluster a WSN through taking advantage of the shortcomings of these protocols (i.e., LEACH, T-LEACH, and MT-CHR), namely centralized density- and threshold-based cluster head replacement (C-DTB-CHR) and C-DTB-CHR with adaptive data distribution (C-DTB-CHR-ADD) protocols that mainly aim at optimizing energy through minimizing the number of re-clustering operations, precluding cluster heads nodes premature death, deactivating some nodes located at dense areas from cluster’s participation, as well as reducing long-distance communications. In particular, in C-DTB-CHR protocol, some nodes belong to dense clusters are put in the sleeping mode based on a certain node active probability, thereby reducing the communications with the cluster heads and consequently prolonging the network lifetime. Moreover, the base station is concerned about setting up the required clusters and accordingly informing sensor nodes along with their corresponding active probability. C-DTB-CHR-ADD protocol provides more energy optimization through adaptive data distribution where direct and multi-hoping communications are possible. Interestingly, our simulation results show impressive improvements over what are closely related in the literature in relation to network lifetime, utilization, and network performance degradation period. 相似文献
Top tensioned strings and beams are often used in civil and marine applications. Typically these members have constant cross sections, and a pronounced, usually linear, tension variation, due to the effects of gravity. In this paper simple, approximate formulas for the natural frequency of such strings are derived, based on asymptotic techniques, while for the tensioned beam case approximate closed-form results are developed by the Wentzel–Kramers–Brillouin method. Both derivations are shown in reasonable detail. While similar work is known for a beam with varying axial tension this is believed to be the first time that a single analytic expression is developed for the full length of the beam. A simple example in which the bottom tension is only 9% of the top tension is analyzed for cases with and without bending stiffness, and the solutions have been compared to the exact solution for the string case and to the results from three finite-element programs for the beam case. The accuracy was found to be very good, even in this situation, in which the tension variation is large. 相似文献
A simple and reproducible chromatographic method for determination of decabromodiphenyl ether (DBDPE) is presented. The mobile phase consisted of aqueous acetonitrile solution. A simple quantitative extraction method using a soxhlet extraction is proposed to extract decabromodiphenyl ether from textile backcoated sample, and, a rapid chromatographic method using spectrophotometric detection, is described for the determination of decabromodiphenyl ether. The proposed method is applied for the determination of the decabromodiphenyl ether in a backcoated textile. Complete methods validation for both the extraction and analytical methods are discussed. Linear calibration curve in a range of 0.3-300.0mg/microL is achieved with a detection limit of 0.1microg. The method is successfully applied to the determination of decabromodiphenyl ether in several backcoated formulations. 相似文献
Solar space cooling is important in the countries of the Arabian Peninsula where nearly half of the total produced electricity is used for air conditioning of residential commercial and public buildings. In Kuwait, large proportion of funds were allocated for research in solar cooling applications. By the year 1985, several small and medium capacity demonstration projects were installed and tested and more were anticipated for the future. These systems used flat plate collectors and small vapor absorption refrigeration (VAR) system of 5 to 10 tons cooling capacity (TR). The first large installation in Kuwait was carried out in the early eighties for a school building. Immediately thereafter, an equally important installation comprising of 300 m2 of flat plate collector area and three 10 TR VAR chillers, was completed in 1983 for an office building of the Ministry of Defense (MOD). These two well instrumented installations were tested for more than one summer season. The system at MOD is the most successful installation and it has been functioning excellently, to-date. Performance results of the system taken during the summer of 1995 have been presented in this paper. 相似文献